This invention relates to an environmentally safe insecticide composition. More particularly, the invention features a specific insecticide formulation consisting of certain fatty acid soaps and pyrethrins together with a stabilizer and carrier, which formulation exhibits improved insecticidal properties as compared with the individual components, is effective in the control of a broad range of leaf eating and other insects, is environmentally safe, and has acceptably low phytotoxicity.
The use of insecticides has greatly enhanced agricultural productivity, but it has become apparent that there are limits to the amount of petrochemical-based materials that safely can be absorbed into the environment. Catastrophic, unanticipated, relatively long term effects experienced with materials such as DDT have increased awareness of the potentially dangerous environmental impact of widespread use of synthetics, contributed to the creation of regulatory agencies charged with protecting the environment, and promoted the development of potent, but apparently less dangerous insecticidal materials made from petrochemicals. These new insecticides are nevertheless far from ideal from the point of view of environmental safety, and sometimes collect in food and fresh water resources.
Recently, natural insecticidal materials such as bacterial preparations lethal to insects have been available commercially. However, the potential of non-bacterial, natural materials having insecticidal properties has largely been ignored, presumably because of the higher cost and lower insecticidal activity of such known natural substances.
Salts of fatty acids, primarily sodium or potassium fatty acid soaps, recently have been used commercially as an insecticide. Compositions having excellent insecticidal properties which exploit these salts are available commercially under the trademark SAFER INSECTICIDAL SOAP. This product accordingly constitutes an exception to the trend noted above. These fatty acid soaps are naturally occurring materials having no known long term environmental effects. They are very effective against mites and soft bodied insects such as aphids and whiteflies, but less effective against other types of insects.
Pyrethrum was used commercially many years ago as an insecticide, primarily in the form of "oleoresin of pyrethrum". Oleoresin of pyrethrum is an archaic pharmaceutical term for an ether extract of the cinerariaefolium variety of chrysanthemum. It contains volatile oils and components having insecticidal properties, called pyrethrins, jasmolins, and cinerins. These materials are known to be toxic to insects, essentially non-toxic to mammals, to lack persistence in the environment, and to be characterized by negligible biological magnification in the food chain.
One major problem with the use of these materials (hereinafter "pyrethrins") as insecticides is their high cost per unit dose. Attempts to extend the efficacy of the pyrethrins to provide economic feasibility have not been commercially successful. An example of such a composition comprising a mixture of saponified organic acids, i.e., salts of coconut oil, and pyrethrins was sold commercially under the trademark Red Arrow about 55 years ago. However, these mixtures did not solve the expense problem because of their high pyrethrin content, about 40% by weight, and because the coconut oil soaps contributed little to their insecticidal efficacy. In fact, most commercially available fatty acid soap compositions contain an excess of alkali which is thought to promotes hydrolysis and inactivation of pyrethrins. Pyrethrin-based insecticides also degrade rapidly in storage and in use.
Other materials which have been used to extend the efficacy of pyrethrins are toxic not only to insects but also to a variety of plants and animals. One material often suggested for use with pyrethrins is piperonyl butoxide. While this type of composition can produce a very potent insecticide, high doses can cause nausea in many animals including man, and the compositions are significantly phytotoxic. Other combinations of insecticides and pyrethrins have either presented similar toxicity concerns or loss of effectiveness due to inactivation of the pyrethrins.
It is an object of this invention to provide an insecticide formulation comprising natural, biodegradable materials which are inexpensive, non-toxic to a wide variety of plants and animals, and effective against a broad spectrum of insect life. Another object is to provide a specific, environmentally safe insecticidal combination of natural products which has a commercially acceptable shelf life, low, acceptable phytotoxicity, and low cost.
These and other objects and features of the invention will be apparent from the description and the claims which follow.